The Top 10 Senate Seats Poised for Potential Change in 2024

The upcoming presidential election is of utmost importance to Democrats as they strive to maintain control of the Senate, due to the challenging landscape. Democratic Sen. Joe Manchin's decision not to seek reelection in West Virginia highlights the favorable 2024 playing field for Republicans. However, if President Joe Biden is reelected, Senate Democrats would have a narrow advantage, thanks to the vice president's tie-breaking role in a evenly divided chamber.

The GOP only needs to gain one or two seats to take control of the Senate, depending on the outcome of the presidential election. West Virginia has been seen as the most likely seat to flip, and with Manchin leaving, Republicans are expected to secure it. Now, attention has turned to the other two red-state seats being defended by Democrats - Montana and Ohio - which are the next most likely to flip. (Rankings are based on CNN's reporting, fundraising, and historical data on state and candidate performance.)

The battle for Senate control this year will serve as a significant political test: Is the race so nationalized that the presidential battlegrounds and the factors influencing the contest are all that matter? (This is especially important due to the considerable overlap between the five states holding key Senate races and the presidential battlegrounds.) Or are the individual candidates, their campaigns, and local issues equally important? The answer will likely determine the outcome of who gains control of the Senate.

Democrats are defending seven of the top 10 Senate seats most likely to flip. An eighth, Arizona, is held by a former Democrat, independent Sen. Kyrsten Sinema, who still aligns with her former party and has yet to confirm if she's running for reelection. Manchin's decision has immediately made the only two Democratic targets on this list - Texas and Florida - much more prominent in the party's 2024 strategy.

Democratic possibilities for Senate control depend on retaining all remaining seats and the presidency, flipping key states like Florida or Texas, or winning the presidency and flipping both Florida and Texas, all while harnessing significant voter turnout. The challenge is compounded by recent polls indicating that former President Trump and GOP front-runner Donald Trump hold an advantage over Biden in potential matchups.

The fate of the Senate rests in the hands of Democratic senators like Jon Tester of Montana and Sherrod Brown of Ohio who may need to distance themselves from the presidential race. Despite their established reputations and individual brands, it remains unclear if they will be able to break through partisan barriers in their respective states. Similarly, Democrats are making the argument that personality traits can triumph over party lines in the races against Sens. Rick Scott in Florida and Ted Cruz in Texas. However, these are costly states that have historically favored Republicans, and investing in them may mean diverting resources from other crucial seats they are defending.

The Democrats may find hope in the fact that GOP primaries are becoming more active despite the National Republican Senatorial Committees' efforts to support a single candidate early on. While contested primaries matter less in West Virginia, Montana, Ohio, Nevada, and Michigan may face divisive GOP races. In Wisconsin, the GOP is waiting for a wealthy businessman to enter the race after missing out on their first-choice recruit. The Republican front-runner in Arizona is known for denying the election results. Pennsylvania is the only state where the GOP has avoided internal conflict, allowing their candidate to directly challenge the Democratic incumbent. It remains to be seen whether the GOP's strategy of recruiting wealthy candidates will pay off, especially given that many of them have not faced much scrutiny in the past.

As the election year begins, there are several key things to watch: the release of fundraising reports from the final quarter of 2023, the sustainability of the Democrats' fundraising momentum, the impact of wealthy GOP recruits self-funding, and the resolution of Republican primaries in Wisconsin with minimal damage to their ultimate nominees.

These rankings will be updated over the course of the year as we get more of those data points.

For now, here are the 10 Senate seats most likely to flip:

1. West Virginia

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Democratic Sen. Joe Manchin of West Virginia

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Democratic Senator Joe Manchin's announcement that he will not seek reelection has diminished any hope the party had of retaining this seat in a state that Trump won by a large margin. Republicans are poised to win the seat, with Governor Jim Justice or US Rep. Alex Mooney as potential nominees. Mooney and his supporters at Club for Growth Action are working to associate Justice, a former Democrat, with President Biden and the Democratic Party. They have pledged to invest millions in promoting Mooney's candidacy.

2. Montana

Mooney is being targeted by a group known as Conservative Americans PAC, which is emphasizing his ties to Maryland and noting the club's opposition to Trump. On the other hand, Justice has the support of both the National Republican Senatorial Committee and Trump, whose endorsement is highly influential in this strongly conservative state.

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Democratic Sen. Jon Tester of Montana

Sen. Jon Tester's reelection bid will determine if popular incumbents can still overcome partisan politics in their states, a test he has successfully passed three times before.

Republicans are excited about their candidate to challenge Tester. Retired Navy SEAL Tim Sheehy has quickly taken to the airwaves to introduce himself to voters, which has helped boost his standing in a potential primary against US Rep. Matt Rosendale. A recent advertisement emphasizes Sheehy's military service while criticizing Tester (and Biden) for being "too liberal to keep us safe." Sheehy also has a super PAC supporting his campaign.

However, the Minnesota native has been the subject of negative headlines - which Democrats have seized upon - including a Semafor story about comments he made in August regarding a desire to return the healthcare system to "pure privatization." (His spokesperson stated that he was criticizing insurance companies and supports protections for pre-existing conditions, as well as honoring Medicare and Social Security commitments.)

The upcoming race provides a prime example of the new strategy of national Republicans to take sides early in a primary. Matt Rosendale, who was defeated by Tester in 2018, is the type of nominee the NRSC is hoping to avoid this time around. Nonetheless, the House Freedom Caucus member is increasingly considering jumping into the race before the March 11 filing deadline.

Following the NRSC's criticism of Rosendale, who was one of eight Republicans that voted to oust McCarthy as speaker, the congressman released a video expressing that he is "heavily considering" running for Senate. He also shared photos of a meeting with Trump at Mar-a-Lago to fuel his potential Senate bid, although this reportedly irked Trump at the time since Rosendale hadn't endorsed him yet. Rosendale eventually did so, but only after Sheehy had already declared his support for Trump months earlier.

Rosendale could benefit from the support of the Last Best Place super PAC, which has been running attack ads against Sheehy without disclosing its donors. The group has been accused by Republicans of being a Democratic front group, but the Senate Majority PAC, tied to Democratic leadership, has declined to comment on its involvement. Democrats are confident that Tester can win against either Republican candidate. Tester himself has aired positive bio ads, highlighting his farming background, commitment to public lands, Second Amendment rights, and defense of the Montana way of life. Additionally, he has promoted his work on the PACT Act, expanding healthcare benefits for veterans exposed to toxic burn pits.

3. Ohio

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Democratic Sen. Sherrod Brown of Ohio

Evelyn Hockstein/Reuters

Sen. Sherrod Brown, a Democrat seeking reelection in a state won by Trump twice, is a top target for the GOP. Leading up to the March 19 primary, the three-term incumbent is able to sit back and watch his potential Republican opponents battle among themselves, while he works to portray each of them as being too extreme.

Following the overwhelming approval of a ballot measure guaranteeing the right to abortion in November, Brown's team released a video compilation of quotes from his Republican challengers, indicating their support for a national abortion ban.

The national GOP has not taken a specific side in this race, but Trump got involved toward the end of last year by supporting wealthy businessman Bernie Moreno. Moreno also has the backing of the state's other US senator, J.D. Vance, who received Trump's support in his own GOP primary in 2022. A recent ad featuring Moreno showcases the former president praising the GOP hopeful, who then emphasizes, "The first thing we have to do is we have to finish the wall."

State Sen. Matt Dolan, the more moderate candidate in the race, began his advertising campaign with a focus on border security, but without explicitly appealing to Trump. Both candidates have significant personal wealth - each having loaned their campaigns $3 million in the third quarter.

4. Pennsylvania

The campaign began with Ohio Secretary of State Frank LaRose, the sole statewide elected official in the race, holding a more prominent position. However, his opponents have been eager to cast doubt on his capability to fulfill conservative expectations following the defeat of an August ballot measure, which was viewed as a precursor to the November referendum on abortion rights.

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Democratic Sen. Bob Casey of Pennsylvania

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Pennsylvania is a high-priority Republican seat with a straightforward GOP primary process, placing it high on the list of competitive races. With former hedge fund executive Dave McCormick as the GOP candidate and no challenge from failed gubernatorial nominee Doug Mastriano, the party was able to start their campaign against Democratic Sen. Bob Casey early. This upcoming race is expected to be Casey's most challenging Senate race as he seeks a fourth term.

China plays a central role in this election, with McCormick proposing six bans to curb what he calls "China's free ride." But his strong anti-China stance appears to contradict his past leadership of significant investments into US exchange-traded Chinese companies while working at Bridgewater Associates, as reported by CNN's KFile. Recently, Casey introduced legislation with GOP Sen. Rick Scott, aiming to compel private investment funds to disclose Chinese assets. In the race, Casey, endorsed by AFL-CIO, presents himself as a populist, while using McCormick's hedge fund history to depict him as out of touch. In a shift, both candidates have opposed the sale of US Steel to a Japanese company. Nevertheless, with Biden's decline in polls, Pennsylvania's uncertainty, and voter concerns about the economy, the Democrats' desired outcome may be more complex than anticipated.

5. Arizona

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Independent Sen. Kyrsten Sinema of Arizona

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Senator Kyrsten Sinema's intentions for reelection remain a mystery, leaving many wondering if it will result in a three-way race. All candidate filings with the secretary of state's office must be submitted by April 8.

Should she decide to run, Republicans are counting on her drawing more votes from the Democratic candidate rather than their own nominee. This strategy is evident in a recent NRSC digital ad attacking Democratic Rep. Ruben Gallego, while also portraying Sinema, who has clashed with Senate Democratic leadership, as a liberal.

Despite national Republicans urging her to move forward after her 2022 gubernatorial loss, Kari Lake remains the front-runner for the GOP nomination. Despite the backing of more established party figures like Wyoming Sen. John Barrasso, Lake continues to contest her previous defeat, even losing a legal case in November. However, with Trump's endorsement and appeal to base GOP voters, Lake will be a tough opponent to beat in the August primary. Although the national party has not ruled out supporting her, running against Lake is an exciting prospect for Democrats. However, the national party is waiting to see how things develop with Sinema before getting involved.

6. Nevada

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Democratic Sen. Jacky Rosen of Nevada

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The Nevada election offers Republicans another chance to gain a Senate seat, as they aim to replace Democratic Sen. Jacky Rosen. In the June primary, there are numerous Republican candidates, but the national party is supporting retired Army Capt. Sam Brown, who was the runner-up in last year's Senate primary.

Nevada supported Biden by a margin of approximately 2 points in the 2020 election, and the Democrats are optimistic that their efforts in this state during a presidential election year, combined with the importance of the abortion issue, will benefit their entire slate of candidates. However, early polling data on a potential match-up between Biden and Trump has caused concern among Democrats. According to a poll conducted by the New York Times/Siena College in late October, the former president is leading the current president 52% to 41% among registered voters. Hispanic voters and White college-educated voters, who are typically a key group for Democrats, are evenly split. Despite Republican awareness that recent federal election results have not been in their favor in Nevada, they see an opportunity to gain support from Hispanic voters. They also believe that even if they do not win this seat, forcing Democrats to allocate resources here that could be used in Montana or Ohio could be considered a victory.

7. Wisconsin

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Democratic Sen. Tammy Baldwin of Wisconsin

Evelyn Hockstein/Reuters

The Republican Party does not currently have a prominent candidate to challenge Democratic Sen. Tammy Baldwin following the decision of their top choice, US Rep. Mike Gallagher to not run. Attention has turned to businessman Eric Hovde, who NRSC Chairman Steve Daines has indicated is in the running. Hovde, who previously lost the GOP nomination for this seat in 2012, is capable of self-funding his campaign, which is an appealing option for Republicans given the late stage in the election cycle for a challenger to enter.

There is uncertainty surrounding whether another wealthy Republican businessman, Scott Mayer, will enter the race, but Daines has expressed a desire to avoid a primary election. "If Eric gets into the race," he informed The Washington Examiner, "we'd be behind Eric." The NRSC's early support for Hovde has also led to frustration from David Clarke, the Trump-aligned former Milwaukee County sheriff, who could disrupt the GOP's efforts in this race if he decides to enter.

8. Michigan

Despite the absence of a major GOP candidate so far, Democrats cannot take too much comfort. Even though Biden narrowly won the state in 2020, Democrats were unable to unseat GOP Sen. Ron Johnson in the last cycle. Additionally, a November Marquette poll found Biden in a close race with Trump among registered Wisconsin voters.

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Democratic Sen. Sen. Debbie Stabenow of Michigan

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Michigan Democrats have largely coalesced around US Rep. Elissa Slotkin - a powerhouse fundraiser - in the race to succeed retiring Democratic Sen. Debbie Stabenow.

Republicans are currently facing a competitive primary in a state they have not won a Senate race since 1994. National Republicans are backing former US Rep. Mike Rogers' return to the race after leaving Congress in 2015, but there is still significant competition. Former US Rep. Peter Meijer, who lost a primary due to his vote to impeach Trump after the January 6, 2021, insurrection, announced his campaign in early November. Additionally, former Detroit Police Chief James Craig and businessman Sandy Pensler have entered the race after Rogers, making the primary even more competitive.

9. Texas

Despite the Democrats' success in Michigan in 2022, the state GOP is currently experiencing disarray. However, Biden's support appears to have weakened compared to 2020, when he secured the state by a margin of about 3 points. A recent CNN poll conducted in the Wolverine State revealed that Trump holds a 10-point lead over Biden among registered voters, with even young voters showing a preference for Trump. Slotkin's campaign manager refuted a December New York Times report, stating that the congresswoman is eager to run alongside Biden.

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Republican Sen. Ted Cruz of Texas

Texas, along with Florida, has become even more significant for national Democrats. It presents a rare opportunity to win a Senate seat and offset the anticipated Republican victory in West Virginia. The Democratic Senatorial Campaign Committee has allocated resources to both states, including funding for communication and research personnel, as well as running digital advertisements opposing the GOP incumbents.

Democratic Representative Colin Allred is gearing up for a primary on March 5, backed by strong fundraising and a high-profile background as a former NFL player. Having previously ousted a Republican incumbent to secure his position in Congress, Allred's campaign is prioritizing health care as a key issue in the upcoming Senate contest. He is emphasizing his support for the Affordable Care Act and vocalizing his stance on abortion rights through the case of Kate Cox - a Texas woman who fought to terminate a high-risk pregnancy. The race is expected to be tough, with Senator Cruz as a formidable opponent despite the surge of small-dollar donations from his detractors. Although highly visible on the national stage, the contest remains Cruz's to lose, given the historical trend of Texas not electing a Democrat statewide since 1994.

10. Florida

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Republican Sen. Rick Scott of Florida

Evelyn Hockstein/Reuters

In Florida, national Democrats are investing in hopes of defeating Republican Sen. Rick Scott. Despite the uphill battle in the red-trending state, they believe there is potential opportunity given Scott's history of narrow wins and his unpopular policy proposals. Democratic former Rep. Val Demings, a high-profile recruit, lost to Sen. Marco Rubio by 16 points in 2022. Scott, who will be seeking a second term, has a vast personal fortune to draw from, but Democrats are determined to highlight his unpopular policy plan and capitalize on his narrow wins in past elections.

Former US Rep. Debbie Mucarsel-Powell is at the center of attention among Democratic candidates leading up to the August primary. She has demonstrated strong fundraising ability, narrowly outpacing the incumbent in the first part of the quarter, excluding his personal contribution. However, her end-of-year fundraising results will be closely watched to gauge the longevity of her momentum.